This is based on a quick script I made to help troubleshoot ANT+ problems with Zwift. It can take the log from an in progress Zwift session and graph out ANT+ signal issues in real time. I cleaned it up a bit and added a help section in case it's useful for anyone else but internally it's still a mess.
You don't need to download anything and can use the page served directly by GitHub Pages: https://kylemacfarlane.github.io/zwift-live-ant/zwift-live-ant.html